The invention relates to a hydrogen-consuming system with a hydrogen-consuming unit and a hydrogen storage system including a hydrogen pressure reservoir and a solid material reservoir and to a method for the operation of such a system.
It is known to store hydrogen either in gaseous form in pressure storage tanks at several hundred bar pressure or in liquid form at cryogenic temperatures in special cooling tanks. Solid material reservoirs are also known, in which the hydrogen can be stored in a solid and released again under defined conditions. However, the storage material is only capable of storing a few percent of its own weight of hydrogen. Such solid material reservoirs are therefore heavy in comparison with pressurized gas reservoirs of the same volume in which gaseous hydrogen is stored under high pressure.
US 2005/0013770 A1 discloses a hybrid reservoir for hydrogen which provides at least two different types of storage reservoirs for hydrogen in a common housing, namely storage in a solid, storage as a compressed gas or storage of hydrogen in liquid form. In one development proposed therein, a solid material reservoir concentrically surrounds a liquid hydrogen storage area.
U.S. Pat. No. 6,651,701 B2 discloses a storage system having a storage part holding gaseous hydrogen and a storage part holding hydrogen stored in a solid reservoir. Depending on the pressures or the available quantity of hydrogen in the one storage part, the other storage part is connected in order to provide hydrogen for the operation of a hydrogen-consuming unit.
Published patent application US 2003/0049501 A1 discloses a hydrogen-consuming system with a fuel cell system as the hydrogen-consuming unit and an associated method for the operation thereof, said system in particular being a fuel cell vehicle. The fuel cell system is provided with a hydrogen storage system comprising a pressure reservoir and a solid reservoir which adsorbs hydrogen exothermically and desorbs it endothermically. The fuel cell system is coupled in parallel via a hydrogen line system with the pressure reservoir and the solid reservoir, a line branch departing from the solid reservoir with a shut-off valve arranged therein joining together with a line branch coming from the pressure reservoir, in which line branch there are a shut-off valve and a pressure-regulating valve, at a junction, from which a supply line leads to the fuel cell system, in which supply line there are a further pressure regulating valve and a further shut-off valve. A cooling circuit is additionally provided, to which are coupled the fuel cell system and the solid reservoir and a radiator, for example a conventional vehicle radiator. The solid reservoir and the radiator are here arranged in parallel branches of the cooling circuit, which are joined together to a line portion leading to the fuel cell system, a regulating valve being arranged in the solid reservoir cooling circuit branch and a radiator bypass line with associated bypass valve being connected in parallel to the radiator. Depending on the operating state of the fuel cell vehicle and in particular of the fuel cell system, hydrogen can be supplied to the fuel cell system from the pressure reservoir or from the solid reservoir and to the solid reservoir from the pressure reservoir. Moreover, the coolant in the cooling circuit can be passed in a controllable quantity via the solid reservoir and the coolant not passed via the solid reservoir may returned to the fuel cell system via the radiator or past the latter via its bypass line. This is intended, in addition to normal operation, also to enable a fuel cell heating mode, in which the coolant is heated by the solid reservoir, which is supplied with hydrogen from the pressure reservoir for this purpose and, bypassing the radiator, is conducted to the fuel cell system. In the normal state at operating temperature, the coolant can transfer heat from the fuel cell system to the solid reservoir in order to assist the endothermic hydrogen release process therein. Switching between the different modes of operation is dependent on a hydrogen pressure sensor on the solid reservoir and a coolant temperature sensor on the fuel cell system.
It is the principal object of the present invention to provide a hydrogen-consuming system with an optimized hydrogen supply and an efficient method for the operation of the system, the hydrogen storage system permitting an elevated hydrogen storage density and having a tolerable weight.